The name Cradle of Humankind reflects the fact that the site has produced a large number, as well as some of the oldest, hominid fossils ever found, some dating back as far as 3.5 million years ago.[2] Sterkfontein alone has produced more than a third of early hominid fossils ever found.[3]

The remains of several partial skeletons of a previously unknown Australopithecan species were found in 2008 near Johannesburg.[4] They have been dated to about two million year ago (mya). A recent re-examination of two partial skeletons of Australopithecus sediba has led to its identification as close to the origin of the genusHomo.[5] Not all palaeoanthropologists agree this is a new species.[6]

A new analysis shows this species had a human-like pelvis, hands and teeth, and a chimpanzee-like foot. In six separate research reports, palaeontologists reported on the anatomy of a juvenile male skeleton, MH1, a female skeleton, known as MH2, and an isolated adult tibia or shinbone, known as MH4. The findings suggest that some species of australopithecine climbed trees, some walked on the ground, and some did both.[7]

"Its small heel resembles that of a chimpanzee more than it does a human. This suggests it likely walked with an inward rotation of the knee and hip, with its feet slightly twisted. This primitive way of walking might have been a compromise between upright walking and tree climbing, the researchers suggest, since A. sediba seems to have had more adaptations for tree-climbing than other australopithecines".[7]

Colleagues in England investigated the teeth. Like other parts of the skeleton, the teeth are a mosaic of primitive and human-like features.[8]